Treatment of lead-sulfid ores.



P. C. H. WEST.

TREATMENT OF LEAD SULHD ORES.

APPLICATTON men NOV. 24. 1915.

Patented May 8,1917.

; UNITED STATES PATENT OFFICE.

PERCY c. n. WEST, or LONDON, ENGLAND.

'- 1 TREATMENT OF LEAD-SULFID ORES.

Specification of Letters Patent.

Patented May 8, 1 917.

Application filed November 24, 1915. Serial No. 63,280.

To all 1/. hom it may concern:

Be it known that l. PERCY CHARLES .HARRY \Vns'r, a subject of-the Kin gof (ll-eat Britain, residing at London. l lngland, have invented certainnew and useful Improvements in and Relating to the 'l reatment ofLead-Sulfid Ores, otwhich the followingv is a specificationyreferencebeing had therein to the accompanying drawing.

According to the known processes for obtaining basic lead sulfate. leadsullid ores In working them it has been found (1) that 1 the ironcompounds contained in the ore or in'the coke are vol at hzed togetherwith the sulfid, even when such compounds are pres- 'ent only in smallquantities; (2) that at the temperature obtaining in the furnaces thereis formed a certain proportion of slag which is difficult to extract;(3) that much, pig lead is produced. (4:) that the properties of thebasic lead sulfate which is obtained are not all that is desired; and(5) the processes l-0pje1a*e with a certain want of uniformity owing.for example, to variations in the temperature of the bed of coke as awhole or to local variations of temperature within me bed of coke.

The object of my nvention is to overcome as far as possible the abovementioned defects, and generally to effect improvements in the knownprocesses for the production 'of basic lead sulfate from lead sulfid.

-Acc0rding to my inventiom the lead sul- "fid is volatilized at acomparatively low temperature for example 1000ll00 C.

Further, according to my invention. in

order to efl 'cctthe volatilization of the lead .sulfi'd at the desiredlow temperature, when "employing a bed of incandescent coke, the

air required to maintain combustion is aspirated through the bed of cokeby means of a fan which also draws in the air required. to

"oxidize the vapors and exhausts the fumes produced, and, in order toassist in maintaining the desired low temperature for the volatilizationof the lead sulfid, a proportion of combustion gases or other neutralgases. for example. carbon dioxid may be admixed with the air requiredfor the combustion of the (()l\'(. y admixing: such gases with the airthe employment of induced draft entirely. is of less importam-e.

When the formation of basic lead sulfate is carried out by the typeofprocess i n which air is drawn into the furnace above the level of thecoke in order to effect oxidation of the sulfid vapors, according to afurther feature of my invention. the quantity of air so I described withreference'to the plant illustrated in the accompanying drawings:inwhieh. a a

Figure l is a longitudinal section of a plant suitable for carrying theinvention into effect.

Fig. 2 is a transverse section on the line 1 K 1 of l.

Fig. 3 is a transverse section on the line 22 ofFig. 1 and Fig. 4 is asection on a larger scale of the feeding device.

The g'alona. is fed from a container;a by a suitable fecdingdevice, fornstance. a screw conveyor (4' into the hopper I; vwithin which may bearrangerhns indicated in Fig. 4, smaller hoppers 71, and 7/ the hoppersthus arranged. having-discharge openings of sucressivelv decreasing sizeby which. means the ore is more accurately directed toward the apex ofthe cone c. l y I The .galena falling on tothe cone. is uniformlydistributed over the surfaceof the bed of incandescent coke (,Z by meansof which it is vaporized at a temperature of about 1000 (1-1100 C. Thevapors of lead sullid thus produced meet a stream .of air passing in ata by which they are partially oxidized and together they pass by 'ay ofr the pipe f into the. clunnber y in .which are provided openings 7:.hav ngfd ape A further quuntlty of air is drawn in through theseopenings and the incandescent vapors are thereby completely oxidized andpartially cooled, the cooled gases passing by way of the conduit throughthe cooling chambers in, l'. 1. and 7. which are preterably constructedof thin metal, in order that the gases may rapidly be cooled. Thesecoolers are of considerable height and depth in relation to their widthand each of the chambers Ir Z A and is, is provided with a diaphragmparallel to the plane. of Fig. 'l causing the gases as indicated by thearrows to travel downwardly from the point at which they enter thecooling chamber and upwardly to the point at which they pass out.

After passing through these cooling chambers which may he provided withopenings having slides. in order that material deposited in them may bewithdrawn, the gases and the solids suspended therein pass by way of thetrunk 11 into the chamber 0, the upper surface otwhich is provided witha plurality of holes p, having collars I to which flannel ba-gs r aresecured at one end by means of suitable clips. 'lhese tlannel bags aresuspeni led from the bars a which are so mounted in the walls of thechamber 1 that they may be pushed backward and forward in a longitudinaldirection and thus the material deposited in the bags may be shaken downon to the iloor oi the chamber 0, from which it may be removed by way ofsuitable openings, conveying apparatus being pri'n'ided if desired toenable the material to be economically removcdf 'lhe gases freed fromsuspended solid matter pass through the bags into the chamber 1? fromwhich by way of the trunk r they pass to the fan w and are discharged bythe shaft 0'.

The air required to maintain the combustion of the coke is drawn bymeans oi the fan '1!) through an opening 7 the size of which by means ofa slide 1 or the like may be varied. and thence between the tirehars 2through the bed of coke (l.

The whole of the. air required for the combustion of the coke, theoxidation of the sulfid vapors and for cooling are thus drawn throughthe several devices by means of one fan, whereas hitherto the airrequired for the combustion of the coke has been fort ed in throughtwyers when a furnace similar to that now employed has been used. The.temperature in the vturnace is, by the method of supplying air nowdescribed kept very uniform and local overheating is prevented with theresult that the whole process operates with remarkable regularity andyields av product of great uniformity of character.

The coke employed should he foundry or furnace coke and the depth of thebed of coke should be relatively considerable, for

instance. about 1.5 meters. The air admitted to the bed of coke shouldbe limited in order to prevent the temperature rising unduly. Thetemperature of' the vapors in the. combustion chamber is kept within thedesired limits. that is to say preferably within the limits betweenwhich they glow with an orange red or orange color, firstly byregulating the draft through the furnace or by introducing with the aira greater or less proportion of combustion gases. for example carbondioxid; and secondly, by adjusting the slides j in order to permit ofthe entrance of a greater or less proportion of air which will thusproduce a greater or less cooling action.

I claim i l. process of treating lead sulfid ores to obtain basic leadsulfate which comprises feeding lead sulfid onto an incandescent bed ofcoke. partially oxidizing the vapors thus formed and then completing theoxidation of the vapors at a lower temperature.

2. process of treating lead sulfid ores to obtain basic lead sulfatewhich comprises feeding powdered galena onto a deep bed of incandescentcoke, volatilizing thclcad sultid at a uniformly low temperature, partially oxidizing the vapors formed and then completely oxidizing thevapors at a lower temperature.

3. A process of treating lead sulfid ores to obtain basic lead sulfatewhich comprises feeding the lead sulfid ore onto a deep bed ofincandescent coke, volatilizing the lead sulfid ata temperature of10001100 C. partially oxidizing the vapors formed and then completelyoxidizing the vapors at a lower temperature.

4. A process for the treatment; of lead sultid ores comprising feedingthe lead sultid on to a bed of incandescent coke while maintaining thebed of coke at a temperaturc below that which injection of a gaseousmixture of the. composition of air would cause it to assume.

5. A process for the treatment of lead sulfid ores comprisingvolatilizing the lead sulfid at a comparatively low temperature in anattenuated atmosphere and oxidizing the vapois produced.

6. A process for the treatment of lead suliid ores comprising feedingthe lead sultid on to a bed of incandescent coke, maintaining the cokein a state of incandescence by aspirating air thercthrough and oxidizingthe vapors produced.

7. A process of treating lead sulfid ores to obtain basic lead sulfatewhich comprises feeding the powdered ore on to a bed of incandescentcoke in a furnace, volatilizing the lead sulfid at a temperature ofabout WOO-HOW (7.. admitting to the furnace above the level of the cokea quantity of air insullicient to oxidize the vapors of lead sulfidcompletely, causing the partially oxito obtain basic leadsulfate Whichcomprises feeding the powdered ore onto a bed of incandescent coke in afurnace, volatihzmg the lead sulfid at a temperature of 1000' 1100 C.admitting to the furnace above the level of the coke a quantity of airinsuificient to oxidize the vapors of lead sulfid con'ipletely, passingthe vapors into achamher and further oxidizing the vapors therein atsuch temperature that the vapors glow with an orange red to orangecolor.

9. A process of treatinglead sulfid ores to obtain basic lead sulfate"which comprises aspirating air through a bed of incandescent coke in afurnace, feeding powdered galena onto a bed of coke, volatilizing thelead sulfid at a ten'lperature of 1000-1100 C., aspirating air into thefurnace above the level of the coke in a quantity insuflicient tooxidize the vapors completely, aspi 'ating the partially oxidized vaporsinto a chamber admitting airto this chamber and effecting the completeoxidation of the lead sulfid. a

10. Appa -atus for'tlie treatment of lead sulfidores comprising afurnace, means for feeding the ore thereto, means for aspirating airtheretl'irough, means for admitting air above the fuel level in thefurnace means for aspirating the gaseous products therefrom, a chamberconnected to saidmeans, means for admitting air to said chamber, aplurality of cooling chambers connected thereto and means connected tothe last of said cooling chambers for aspi-

